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arXiv 1808.01088astro-ph.IMastro-ph.HE
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后相关波束形成器用于瞬态信号的时域研究

Post-correlation beamformer for time-domain studies of pulsars and transients

Jayanta Roy, Jayaram N. Chengalur, Ue-Li Pen

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24 pages, 9 figures, accepted for publication in The Astrophysical Journal
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摘要：

我们提出了一个详细的分析后相关波束形成（即波束形成只涉及相位总和的相关性的不同天线的电压在一个阵列），并比较它与传统上使用的非相干和相位波束形成技术。使用的数据从GMRT，我们表明，后相关波束形成的结果在一个许多倍的增加，在信号噪声的周期性信号，从单脉冲事件，如快速射电暴（FRB）的假触发的数量减少了几个数量级。这种差异主要是因为后相关波束包含较少的红噪声以及较少的射频干扰。后相关光束也可以比非相干或相控阵光束更容易校准。我们还讨论了两种不同的后相关波束形成模式，即（1）从相干光束中减去非相干光束和（2）相位相加的相干光束。这两个波束形成技术的计算成本，以及它们的适用性的研究的雷达和FRB进行了讨论。这里讨论的技术将是所有即将到来的调查与干涉阵列的兴趣。最后，我们描述了一个时域调查与GMRT使用后相关波束形成作为案例研究。我们发现，后相关波束形成将提高目前的GMRT时域调查的灵敏度的约2倍，周期为几百毫秒的雷达，甚至更慢的雷达的许多倍，使其成为最敏感的调查雷达和FRB在低和中射频。

英文摘要：

We present a detailed analysis of post-correlation beamforming (i.e. beamforming which involves only phased sums of the correlation of the voltages of different antennas in an array), and compare it with the traditionally used incoherent and phased beamforming techniques. Using data from the GMRT we show that post-correlation beamformation results in a many-folds increase in the signal-to-noise for periodic signals from pulsars and several order of magnitude reduction in the number of false triggers from single pulse events like fast radio bursts (FRBs). This difference arises primarily because the post-correlation beam contains less red-noise, as well as less radio frequency interference. The post-correlation beam can also be more easily calibrated than the incoherent or phased array beams. We also discuss two different modes of post-correlation beamformation, viz. (1) by subtracting the incoherent beam from the coherent beam and (2) by phased addition of the visibilities. The computational costs for both these beamformation techniques as well as their suitability for studies of pulsars and FRBs are discussed. Techniques discussed here would be of interest for all upcoming surveys with interferometric arrays. Finally, we describe a time-domain survey with the GMRT using the post-correlation beamformation as a case study. We find that post-correlation beamforming will improve the current GMRT time-domain survey sensitivity by ~ 2 times for pulsars with periods of few 100s of millisecond and by many-folds for even slower pulsars, making it one of the most sensitive surveys for pulsars and FRBs at low and mid radio frequencies.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

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